My apologies to everyone who generously contributed their time to this question. My free time for playing around with things like this has virtually disappeared, so I am unable to test any of these answers. Thanks again for your help!
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zpletanMar 10 '11 at 21:58

Since installing 11.10, this question once again intrigues me, and I am willing to test.
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zpletanNov 17 '11 at 4:38

Ok, but on Ubuntu 10.10 there is not /etc/X11/xorg.conf ... where we have to add those lines for enable SHMConfig? Regards!
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Martín CascoJan 31 '11 at 20:33

You can create a xorg.conf with this data. Once you complete the testing, you can remove the xorg.conf. Any changes to this file require to restart the X server (typically, logout and log in again).
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user4124Jan 31 '11 at 20:34

I've read some people who has created this field on Maverick and X did not start till, with a Live Session, deleted that field.
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Martín CascoFeb 1 '11 at 11:39

OK, my touchpad doesn't detect more than one finger, but can I somehow emulate it by detecting more pressure? (e.g. EmulateTwoFingerMinZ/W which I don't know how to use.)
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zpletanFeb 1 '11 at 17:32

Sure. Send the output of synclient -l so that we can see what your existing values for EmulateTwoFinger* are. In addition, write the name of your touchpad (the output of xinput list).
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user4124Feb 1 '11 at 17:42

Or, for readability, follow these steps instead, which do the same thing:

Create a file called "psmouse.conf" in /etc/modprobe.d:

sudo vim /etc/modprobe.d/psmouse.conf

Add the following line to this file, and save:

options psmouse proto=imps

Lastly, reload the drivers:

sudo modprobe -r psmouse
sudo modprobe psmouse

While this isn't two-finger scrolling, it's the next best thing, and the only type of touchpad scrolling that I've been able to get working on this platform. I'm pretty happy with it, and I hope it helps others.

Also, note that this is a bit of a hack, as the touchpad is loaded as a ImPS/2 Generic Wheel Mouse, and the Touchpad tab disappears from the Mouse Settings menu. However, this is a lot less annoying than having to drag the mouse pointer to the sidebar everytime I want to scroll.

Lastly, I haven't yet rebooted on Linux Mint 11 (not that it matters much here), so the modprobe commands may need to be added to a startup script, if the edge scroll doesn't survive the reboot. However, on Ubuntu 12.04, the one that matters on AskUbuntu, the scroll continues to work even after the reboot.